1. Field of the Invention
The present invention relates to a canister for use in an evaporated fuel treatment device of an internal combustion engine, a method of manufacturing a canister, and a method of manufacturing a sealed container in a canister.
2. Description of the Related Art
From JP-A-2000-186635 and so on, there is known a canister for use in an evaporated fuel treatment device for an internal combustion engine, having an adsorptive material chamber which contains an adsorptive material for adsorbing evaporated fuel; a tank port connected to a fuel tank; a purge port connected to a suction port of the engine; and an atmospheric port opened to the atmosphere. The canister disclosed in this publication is proposed by the present applicant, and activated carbon is used as the adsorptive material.
Moreover, from JP-A-10-339218 and so on, there is known an evaporated fuel treatment device of using, as an adsorptive material to be charged in a container of the evaporated fuel treatment device, an activated carbon adsorptive material which is substantially uniformly provided, on the surface of a particulate adsorption base material made of activated carbon, with thermal storage particles made of metal material such as iron or copper having a large thermal conductivity and a large thermal capacity as compared with the activated carbon.
Furthermore, from JP-A-11-152466 and so on, there is known a thermal storage material microcapsule whose average particle diameter is set to 0.1 to 25 μm and in which a weight ratio of a thermal storage material in a microcapsule solid is set to a range of 60 to 75%, as a thermal storage material microcapsule utilizing latent heat (melting or coagulating heat) in addition to sensible heat of the thermal storage material itself. In the publication, it is described that this microcapsule is used as a thermal storage material or a heat conveying medium for use in heating a building, a house or the like.
In the canister for the evaporated fuel treatment device of the internal combustion engine, as disclosed in JP-A-10-339218, a temperature rise of activated carbon during fuel adsorption and a temperature drop of activated carbon during purging of an adsorptive fuel are restrained by use of the sensible heat of the thermal storage particles. Therefore, in order to improve the restraining effect, it is necessary to use the thermal storage particles having large specific heat and large gravity, and thus, there has been a first problem that weight of the canister increases.
To solve the problem, the thermal storage material microcapsule disclosed in JP-A-11-152466 is mixed with an adsorptive material such as activated carbon, and the mixture is disposed in the adsorptive material chamber, and the temperature rise or drop of an adsorptive material such as activated carbon is restrained by use of the latent heat of the thermal storage material in the microcapsule. This is supposed to be convenient because the temperature change of the adsorptive material can be effectively restrained by use of the thermal storage material microcapsule which is lighter than the thermal storage particles utilizing the sensible heat. However, since the film forming the thermal storage material microcapsule is made of thin resin, there is a fear of a second problem that gasoline vapor (HC) as fuel vapor of the internal combustion engine passes through the film to change a melting point of the thermal storage material.
Moreover, in JP-A-2000-186635, there is known a canister that has an adsorptive material holding filter for holding the adsorptive material to be stored in the adsorptive material chamber.
Furthermore, from JP-A-2003-311118 and so on, there is known a latent heat storage type adsorptive material constituted of the thermal storage material and the adsorptive material containing in the microcapsule a phase change substance which absorbs and discharges the latent heat in response to the temperature change. On the surfaces of the adsorptive material particles is provided the thermal storage material having a particle diameter which is smaller than that of the adsorptive material.
In JP-A-2000-186635, there are not any measures for improving an adsorption performance of the adsorptive material. In JP-A-10-339218, the sensible heat of the thermal storage particles is utilized as the measures for improving the adsorption performance of activated carbon. However, there is a problem that there is little effect of improving the performance because the sensible heat is utilized. Furthermore, in JP-A-2003-311118, there is not referred to any canister for use in the evaporated fuel treatment device of the automobile internal combustion engine.